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  <title>Document</title>
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<body>
  <script>
    let num =  [15, 19, 21, 33, 18, 24]
    let num2 = 0
    for(let i = 0; i < num.length; i++){
      num2 += num[i]

    }
    document.write(`平均值为${num2 / num.length}`);
  </script>
</body>
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